Device for sampling exhaust stack effluent

ABSTRACT

Effluent discharging into the atmosphere from dry exhaust stacks is sampled by employing an effluent-gathering probe capable of obtaining representative samples of the total effluent exhausted through the stack. The probe travels on two axes in a cross sectional plane of the stack so as to move the probe in a spiral path across the radius of the stack to obtain homogeneous samples of the exhaust emissions.

United States Patent [1 1 [111 3,885,437 Reagan May 27, 1975 DEVICE FORSAMPLING EXHAUST STACK EFFLUENT Primary Examiner-James J. Gill AssistantExaminer-Anthon V. Ciarlante [75] Inventor Paul Reagan Kingston TennAttorney, Agent, or F [rm-Jahres E. Denny; David S. [73] Assignee: TheUnited States of America as Zachry; Earl L. Larcher represented by theUnited States Energy Research and Development Administration,Washington, DC. [57] ABSTRACT [22] Filed: Feb. 26, 1974 Effluentdischarging into the atmosphere from dry ex- PP 9 haust stacks issampled by employing an effluentgathering probe capable of obtainingrepresentative [52 US. Cl 73/421.5 A Samples the total effluhhtexhausted thmugh the 51 Int. Cl 001 1/24; GOln 1/26 stack- The Probetravels on two axes a cross [58] Field of Search 73/4215 A 4215 R 422 Rtional plane of the stack so as to move the probe in a spiral pathacross the radius of the stack to obtain ho- [56] References Citedmogeneous samples of the exhaust emissions.

UNITED STATES PATENTS 3 Claims, 2 Drawing Figures 2,926,527 3/1960Crandall 73/4215 A 1 DEVICE FOR SAMPLING ExuAusT'sTA'c'i; r

EFFLUENT l The present invention relates generally to sampling exhauststack effluent, and more particularly to 'a mechanism for displacing aneffluent-gathering probe to obtain homogeneous samples of: the effluen't' throughout the entire cross section of the stack. This invention wasmade in the course of, or under, a contract with the United StatesAtomic Energy Commis- SlOn.

Regulation of the quantity and types of effluent discharged into theatmosphere has been a major pollution control problem. A considerablepercentage of this air-borne pollution is discharged from dry stacks.The effluentemanating from such stacks has been brought under control toa significant extent by using various precipitators and dust collectingsystems; however, it is application in practical use to thereby enableothers skilled in the art to best utilize the invention in variousembodiments and modifications as are best adapted to the particular usecontemplated.

Described generally, the efflluent-sampling apparatus of the presentinvention is of the type in which a vacuum operated probe is placedwithin a dry exhaust stack or conduit for intercepting and capturing aportion of the effluent passing through the conduit and conveying thecaptured effluent to a suitable container for subsequent analyses. Suchcontainers include filters for removing the particulate matter from thecaptured effluent as are well known in the art. The improvement stillnecessary to monitor the actual discharge of the material into theatmosphere to insure that the effluent collecting systems are in properworking order. The accuracy in obtaining these measurements issubstantially dependent upon gathering representative samples of theeffluent being discharged. If the velocity, particle concentration, andpath profiles of the exhaust gases were homogeneous across the exhauststack, then such representative samples could be readily obtained.However, such ideal conditions seldom exist since the normal conditionswithin the exhaust stack show that the velocity and concentration of thedust particles vary significantly from point to point throughout anygiven cross section of the stack.

Accordingly, it is the primary aim or objective of the present inventionto provide a device for gathering representative samples of the exhausteffluent throughout the entire cross section of a dry exhaust stack.This apparatus comprises a fixture disposed within the stack, atubulation supported by the fixture and projecting along thelongitudinal axis of the stack, a rotatable shaft disposed within thetubulation, an arm secured to the shaft and extending in a directionorthogonal to the latter with this arm having a length substantiallycorresponding to the radius of the stack and displaceable in a crosssectional plane of the latter in response to shaft rotation, slide meanscarried by the arm, an effluentgathering means affixed to the slidemeans, gear means coupling the slide means to the tubulation foreffecting displacement of the effluent-gathering means along the arm inresponse to rotation of the shaft.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

In the accompanying drawing,

FIG. 1 is a vertical section view of an exhaust stack showing thepresent effluent-gathering probe of the present invention; and

FIG. 2 is a fragmentary view taken along lines 2-'-2 of FIG. 1 showingthe paths of the probe within the exhaust stack.

A preferred embodiment of the invention has been chosen for the purposeof illustration and description, The preferred embodiment illustrated isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. It is chosen and described in order to best explain theprinciples of the invention and their rangements aspreviously knowninvolves an arrangement wherein the probe is moved across the radius ofthe conduit while being rotated about the longitudinal axis of theconduit so as to generate a sample-gathering path defined by anarchimedean spiral.

As shown in the drawing, the present invention is disposed in a dryexhaust stack 10 wherein the effluent travels in the direction shown byarrow 11. A frame or fixture 12 is placed within the exhaust stack 10for'supporting the probe-moving device of the present invention. Thisframe 12 is of a construction which provides minimal resistance to theflow of the exhaust gases. A sleeve or tubulation 14 is fixed to theframe and projects from the latter along a path corresponding to thelongitudinal axis of the exhaust stack 10. This tubulation, in turn,houses a rotatable shaft 16 which is driven by a suitable drive motor,e.g., a hydraulic, pneumatic, or electrical motor supported by theframe, as shown at 18. The shaft 16 projects beyond the lowermost end ofthe tubulation l4 and is coupled to a flange-like structure 20 which hasa portion thereof projecting in a vertical direction parallel to theshaft but radially offset therefrom as shown. An arm 22 is secured tothe offset portion of the flange and projects in a direction orthogonalto the axes of the shaft 16 to a location adjacent to the interior wallof the stack so as to span essentially the entire radius of the stack.The arm 22 is provided at the end thereof remote to the flange 20 with ablock-like structure 23 which, together with the flange, providessupport for a worm gear 24. The worm gear is rotatably disposed at oneend thereof in block 23 while the other end of the worm gear ex tendsthrough and is rotatably carried by the offset portion of the flange 20.The worm gear 24, in turn, supports a coneshaped probe 26 having asuitable opening at one end thereof facing upstream with respect to thedirection of the effluent discharge. The probe 26 threadedly engages theworm gear 22 so that rotation of the latter will move the probe alongthe worm gear in either direction so as to traverse the radius of theexhaust stack. The worm gear .24 is provided with the suitablewell-known direction-changing devices contiguous to the block 23 or theflange 20 for reversing the direction of probe travel.

To provide rotation of the worm gear 24 for displacing the probe 26, abevel gear 28 is affixed to the end of the worm gear projecting throughthe flange 20. This gear 28 is in mesh with a stationary bevel gear 30affixed to the tubulation 14 so that'upon rotation of the shaft 16,flange 20 rotates about the axis of the stack, with this latter rotationcausing the bevel gear to rotate the worm gear 24. Thus, as shaft 16rotates to move the probe in a radial direction through the rotation ofthe worm gear 24, the probe is also driven about the longitudinal axisof the exhaust stack to generate a spiral path about the cross sectionof the exhaust stack as generally shown by the arrows in FIG. 2. Inorder to insure the desired exposure of the probe to the effluent, thedistance between adjacent teeth on the worm gear or the rotationalvelocity of the probe may be selectively varied. The effluent gatheredby the probe is conveyed to a suitable container, not shown, by couplingthe probe to a suitable vacuum source, not shown, as is well known inthe art. The vacuum line 32 coupling the probe to the vacuum sourcepreferably extends through the shaft 16 to assure that the line does notin terfere within the movement of the probe.

As various changes may be made in the form, construction, andarrangement of the parts herein without departing from the spirit andscope of the invention and without sacrificing any of its advantages, itis to be understood that all matter herein is to be interpreted asillustrative and not in a limiting sense.

What is claimed is:

1. An apparatus for obtaining a substantially homogeneous sampling of aneffiuent stream flowing through an elongated dry stack, comprising afixture disposed within said stack, a tubulation supported by saidfixture and projecting along the longitudinal axis of the stack, arotatable shaft disposed within said tubulation, an arm secured to saidshaft and extending in a direction orthogonal to the latter with saidarm having a length substantially corresponding to the inner radius ofsaid stack and displaceable in a cross-sectional plane of the latter inresponse to shaft rotation, slide means carried by said arm, aneffluent-gathering means affixed to said slide means, gear meanscoupling said slide means to said tubulation for effecting displacementof said effluent-gathering means along said arm in response to rotationof said shaft.

2. The apparatus claimed in claim 1, wherein said arm and saideffluent-gathering means are displaced simultaneously for driving saideffluent-gathering means along a path defined by an archimedean spiral.

3. The apparatus claimed in claim 2, wherein said slide means is a wormgear, said effluent-gathering means is a probe having aneffluent-receiving opening at one end thereof and coupled to a vacuumsource, and said gear means comprises a stationary bevel gear affixed tosaid tubulation and a rotatable bevel gear affixed to said worm gear andin mesh with said station-

1. An apparatus for obtaining a substantially homogeneous sampling of aneffluent stream flowing through an elongated dry stack, comprising afixture disposed within said stack, a tubulation supported by saidfixture and projecting along the longitudinal axis of the stack, arotatable shaft disposed within said tubulation, an arm secured to saidshaft and extending in a direction orthogonal to the latter with saidarm having a length substantially corresponding to the inner radius ofsaid stack and displaceable in a cross-sectional plane of the latter inresponse to shaft rotation, slide means carried by said arm, aneffluentgathering means affixed to said slide means, gear means couplingsaid slide means to said tubulation for effecting displacement of saideffluent-gathering means along said arm in response to rotation of saidshaft.
 2. The apparatus claimed in claim 1, wherein said arm and saideffluent-gathering means are displaced simultaneously for driving saideffluent-gathering means along a path defined by an archimedean spiral.3. The apparatus claimed in claim 2, wherein said slide means is a wormgear, said effluent-gathering means is a probe having aneffluent-receiving opening at one end thereof and coupled to a vacuumsource, and said gear means comprises a stationary bevel gear affixed tosaid tubulation and a rotatable bevel gear affixed to said worm gear andin mesh with said stationary gear.